This invention relates to an angle spirit level having a basic body element and a bubble element which are connected to each other whereby the bubble element can turn around an axis in its inclination relative to the basic-body-element.
Angle spirit levels are used according to the prior art in order to prove whether the surface or the side area of an object is straight, horizontal or vertical. In order to carry out this examination the basic body element of the spirit level is held on the surface or the side area of the object. The air bubble of the bubble element, which is partly filled with a liquid, indicates whether the wanted geometric arrangement is achieved.
One problem with the prior spirit levels arises when the directions to be examined are not exactly horizontal and not exactly vertical but have d certain inclination.
Bubble-elements have been used before which can be turned having regard to their inclination to the basic element of the spirit level. The measured angle is correct if after having put the spirit level on the object, the air bubble is within a particular area which shows that the air bubble is within a bubble element which is correctly turned a certain angle as indicated above. It has been observed that the prior art spirit level elements, namely with bubble elements which are turnable in respect to their inclination will sometimes give results which are not sufficiently correct. In order to obtain an exact measurement of an angle the body of the spirit level must be positioned exactly along a so-called line of steepest gradient (falling-line). If the body of the spirit level is outside of this line, the result is a corresponding error of the bubble element which can be turned relative to its inclination.
Therefore, it is an object of the invention to overcome the difficulties of the prior art.
The handling of the spirit level must be easy and positive.
This technical problem may be solved by this invention by creating an adjusting bubble element which is fastened on the main body of the spirit level whereby its middle position is parallel to an axis around the bubble element and can be turned in its inclination towards the main body of the spirit level.
This invention is based on the insight that by using such an adjusting bubble element it can be assured that the spirit level can be aligned exactly along the wanted line of steepest gradient with the consequence that errors within the adjustable bubble element are substantially reduced or obviated.
Further it is assured that a user of the spirit level will find the function and effectiveness of this device very easy to understand.
That means the handling of this new and inventive device is relatively easy in practice. The adjusting bubble-element is adjusted to be exactly perpendicular to the line of steepest gradient, i.e. a horizontal line. Thereby, the axis around which the bubble element is pivotably arranged in respect of the basic element is also aligned horizontally; namely perpendicular to the steepest gradient with the consequence that the plane surface in which the bubble element is pivotable is an exact vertical plane, in which the error, named above, cannot occur.
According to a preferred embodiment of this invention, the main body of the spirit, level has an essentially L-shaped cross-section whereby the adjusting bubble element is situated on one angle side, which is angled at 90 degrees (90xc2x0) to the other angle side which is carrying the pivotable bubble element. By this arrangement the adjusting bubble element can have a relatively large size with the consequence that it is easily readable.
According to this invention it is further proposed to put the bubble element which is pivotable relative to the basic element into a cylindrical box or case the central axis of which is identical to the axis around which the bubble element turns relative to its inclination. It is thus possible to get the position of the bubble element in the main body in a very simple way of installation.
Advantageously, the case can be provided with a scale ring on the spirit level with the consequence that an exact pre-adjustment is possible for the bubble element. This scale ring can also carry a scale concerning the percentage inclination as well as gradations.
Due to the fact that certain inclinations will occur very often it is possible to arrange a raster at the scale ring for these inclinations, for example in five degree steps.
This raster advantageously co-operates with raster elements which are arranged on a cover element.
Due to pollution an abrasion of the raster or the raster elements takes place over time but it is easy to change them with the described embodiment.
The cover element will advantageously have a lateral convexity into which the rim of the scale ring is installed and can be moved by way of an opening in the convexity, whereby a pre-adjustment of the bubble element is possible. Further, the cover element can be provided with a window in order to be able to read the markers on the scale ring.
Embodiments of the invention will now be described, by way of example, with reference to the following drawings, in which: